Multiple-step partial oxidation method



Dec. 26, 1933. I

y J.H. JAMES MULTIPLE-STEP PARTIAL OXIDATION METHOD Original Filed OctINVENTOR Patented Dec. 26, 1933 MULTIPLE-STEP PARTIAL OXIDATIO METHODJoseph Hidy James, Pittsburgh, Pa., assignor to Clarence P. Byrnes,trustee, Sewickley, Pa.

Original application October 21, 1924, Serial No.

Divided and this application May 26,

1933. Serial No. 673,010

9 Claims.

The figure is a diagrammatic view showing one form of apparatus forlcarrying out my invention.

This application is a division of my copending application Ser. No.745,025, led October 21, 1924, and relates particularly to thecontinuous recycling method therein disclosed in which a portion of thetail gas is bled out of the system and a fresh portion of hydrocarbonand oxygen is added. This is fully explained and described in the parentapplication of which the following is a true copy.

The present invention relates to the partial oxidation of hydrocarbons,preferably in gaseous form, though it may be in vapor form or in amixture of' both forms. For example, I may employ natural gas, Whetherdry or wet, or gaseous hydrocarbons from any source, as for example,coke oven gases, the gas from the low temperaturecoal carbonizationprocesses, or the gases from the cracking of petroleum oils whichcarryboth saturated gaseous hydrocarbons as well as unsaturatedhydrocarbons belonging to the olefin series. I may also vaporize liquidhydrocarbons and-mix the vapor with gases which are gaseous at normaltemperatures and pressures, or may use the vapor alone in the processwithair or oxygen admixture, etc. I may also add water vapor or steam tothe mixture before it reaches the reaction zone. I may also apply themethod to liquefied or partially liquefied gases, as for example,liquefied propane-butane or liqueed ethane-propane-mixtures. In suchcase, the gases when released from high pressure, pass into gaseous format lower pressures and are mixed in this form with air or oxygen in myprocess. In all cases, the hydrocarbon-air mixture is in gaseous phase,whether a true gas is used or a hydrocarbon vapor or a mixture of both.If hydrocarbon vapor is used, either with or without hydrocarbon gas, Iprefer to use the vapor of the more volatile hydrocarbons, such asgasolines or naphthas.

Taking, for example, the process of my copending applications, Ser. No.132,570, filed November 21, 1916 (now Patent 1,675,029, granted June 26,1928) and Ser. No; 695,194, filed February 26, 1924 (now Patent1,588,836, granted June 15, 1926) which relates to the formation offormaldehyde and formic acid from hydrocarbons preferably in gaseousform, the amount of such industrial prod- 0 ucts obtained in one passageover the catalyst is relatively small, as the time of sojourn in theactive-catalytic region should be low, due to the decomposition of theformaldehyde if the time of sojourn is at all extended.

To Overcome this difficulty, one feature of my,

present invention relates to returning the .major portion of the gas andoxygen, or vapor and oxygen, or gas, vapor and oxygen mixture in thetail gas to the catalytic inlet for repeated treatment, adding fresh gasor vapor or both and oxygen to t) replace the amount taken out in thecycling, and maintaining a substantially uniform set of tem,- peratureand pressure conditions in the apparatus, while at the same timesubjecting the major portions of any one mixture to repeated passagethrough the catalytic zone.

If, to overcome this difilculty, an extended series of catalyticfurnaces is employed with scrubbing systems between them so that themixture after 'passing through the first catalyst is passed 70 throughthe scrubber to take out the industrial product, and then passed` on toanother catalytic furnace and so through a series, with or withoutadding fresh vapor and gas mixture or both with oxygen after eachscrubbing `operation before passing to the next catalyst, the expense ofthe operation becomes high if, for example, from ten to thirty of suchfurnaces are arranged in series.

I have found that I can carryrout this operation with lone reaction zoneand after taking out so the industrial product or part thereof from thetail gas can return the remaining exit gas or the major portion thereofto the apparatus, addlng fresh gas or vapor or both with oxygen or airto replace the portion orportions removed, 35 and can maintainsubstantially constant conditions in the system, so that any one portionof.

the mixture will cycle through the apparatus a large number of times,thus greatly increasing the recovery at fairly low cost. The totalamounts withdrawn are preferably equal to the volume of fresh mixtureadded in each cycle, and

of course, vthe smaller the volume of tail gas discarded, the smallerwill be the volume of yfresh inlet mixture' and the greater the numberof times 95 which the major portion of the mixture will cycle throughthe catalyst, thus giving a greater conversion of the intermediateoxidation products by the oxygen of the mixture. By tail gas in this 10oconnection, I mean the gas remaining after the taking out of thecondensible products from the mixture passing from the catalyticfurnace.

Other features of my invention relate -to the use of intensifiedoxygen", that is, oxygen in a.

more active form than that in air at atmospheric pressures; in using ashort time of sojourn in contact with the catalytic material; incontrolling the temperature `in the reaction zone; in applying heat tothe mixture and regulating the same;

vsystem without passing through the ozonizer,

in applying pressure and varying it in the supply system.

I will now describe the form of apparatus shown in the drawing, it beingunderstood that this may be varied within the scope of my invention.

In the drawing, 2 is an air pump and 3 is an ozonizer through which theair may be passed to increase the activity of the oxygen in the airstream. 4 is a valved by-pass around the ozonizer, so that the air maybe passed direct into the whenever desired. The air then preferablypasses to a constant pressure device 5, having a connected liquidvessel` 6 with va small exit` '1. From the constant pressure device, theair passes through tube 8, having a valve at 9 and past a visible flowmeter 10 of the glass tube liquid type and into a mixer 1l. The supplyof gas or vapor or both passes to a pump 12, thence to a constantpressure device 13, having one tube leading into the lower part of theliquid in a vessel 14 with a small exit 15, at which the surplus may betaken off and may be burned. From the constant pressure device 13 thehydrocarbon gas or vapor or both passes through tube 16 valved at 16a,through visible flow meter 17, and thence into the supply tube 8 leadingto the mixer.

From the tail gas pump 18, which is a circulating pump, a tube 19 leadsto a constant pressure device 20 having one tube connected to a liquidvessel 21, with upper small outlet 22 from which a small proportion ofthe tail gas is taken off and may be burned, if it is combustible. Fromconstant pressure device 20, a tube 23, valved at 24, `leads to flowmeter 25 and thence to the supply pipe 8 and the mixer 11. The mixer ispreferably provided with a series of baffles giving a tortuous course tothe mixture and insuring better mixing. From the mixer, the mixturepasses into a moistening device 26, in which water vapor is added to themixture, which then passes throughra safety tube 27, lled with propermaterialto prevent back flashing, into a tube 28 having a connectedmanometer 29. The tube 28 leads into a circular passage 30, formed inthe bottom of the catalytic furnace 31, this having a series of holesthrough which the mixture enters the furnace chamber. This bottom isheated by gas burners 32, the supply to which is valved, so that thepreheating may be carefully regulated to supply the requisite amount ofheat to the mixture without raising the temperature too much or beyondthe desired limit in the catalytic zone. The temperature must becarefully regulated and held within certain limits; and the proportionsof air with gas or vapor or both must be carefully regulated, all as inmy previous filed applications. The preheated mixture thus regulatedpasses through a catalytic f screen 33, having in contact therewith oradjacent thereto a thermocouple leading to an external indicator 34, bywhich the temperature can be seen at any moment. The catalyst preferablyconsists of the complex oxides or compounds of metals having a varyingvalence. All parts of the complex may consist of oxides of the samemetal or of different metals. For example, an excellent catalyst in thisconnection consists of the so-called blue oxides of molybdenum whichcontain molybdenyl molybdonate (MOozMoOa) and molybdenyl andmolybdenite, and are probably all chemical compounds of two or moreoxides of molybdenum representing different states of oxidation. Thesecomplexes may be regarded as salts, that is, compounds of one or morebasic with one or more acid oxides.

Other complexes of value for such catalysts are chromic chromateCrzOaCrOa, tungsten tung- Uranyl uranate UOzUOs Cobalt molybdate CoOMoOsCobalt molybdite CoOMoOz Di-uranyl vanadate (U02)Vz05 etc.

These metals whose complexes I prefer to employ as Athe acid part of thecatalyst, since I have found them to be of high activity in this field,are the metals of high melting point electronegative low-atomic-volumehaving an atomic weight above 40. These metals appear on the Lothar-Meyer diagram of the periodic series beginning on the descending side ofthe third peak, descending side of the fourth peak and the descendingside of further peaks developed since the date of this diagram. Theclass includes the following metals: titanium, vanadium, chromium,manganese, zirconium, niobium, molybdenum, tantalum, tungsten, anduranium. The basic oxides may be the lower oxides of these metals or maybe the oxides of iron, copper, nickel, lanthanum, cobalt, thorium andthe eight or nine rare earth metals. In both acid or basic portionsthere may be, of course, two or more of these combined.

The upper part of the furnace vessel 31 preferably projects above theenclosing furnace chamber 35, and its top portion 36 is preferablycooled as by air blasts or water cooling or in any desirable manner (notshown). The catalyst also should be as thin as possible to give a verysmall time of sojourn to the mixture therein, andthe mixture should betaken away from the catalyst and cooled as rapidly as possible to avoiddecomposition of the products after formation. The time of sojournshould be between one-quarter of a second and four seconds, and ispreferably less than one second. From the upper portion of the catalyticchamber, a connection 37 leads through a condenser 38, having the properwater or other liquid connections 39 and 40. There is preferably acounterow of the cooling liquid upwardly through this condenser aroundthe coiled I pipe leading through it, and the pipe 37 then leads asusual in such sampling types of pipettes. From this sampling device, thetail gas may pass through a water scrubber or scrubbers 47 of the bulbedtype shown at 41, and thence to the pump; or it may bypass to a scrubber48 of the chemical type, such as vessels contaning NaH S03, if desired,and thence to the tail gas pump 18. The gas may also pass directly fromthe bulbed water scrubbers to the pump.

The pumps are all preferably of the variable speed variety and theproper speeds are given them to keep the proportions, pressures, speeds.speed of ow, etc. fairly constant after an equilibrium has beenestablished in the apparatus.

In starting the apparatus, I preferably apply heat to thefurnace andcycle through the 'entire apparatus the gas or vapor or gas and vapormixture without oxygen or air, allowing a part of the tail gas to passoff until the system is filled When this tail gas taken off issubstantially uniform in character, the apparatus is in completeoperation and the regular process proceeds under substantially constanttemperature and pressure conditions, the temperature being regulated byregulating the burners, supplying external heat to the mixture, and thepressure beingregulated by regulating the take-off caps. During thepreparatory operation, the temperature is preferably gradually raised.If air is used at ordinary atmospheric pressure, thev mixture shouldbein the proportion of one volume of gas or gas and vapor to not overthree and one-half volumes of air'. .In case I use "intensified oxygeneither by supplying pure oxygen in whole or in part or by running theapparatus under portions in the mixture should be changed.

As regards temperature in the catalytic zone,

Ithis should general be somewhat lower than v in the one-passage casesbefore referred to. In the cases hereafter described where pure oxygenis used, the temperature shouldnot rise above 500 G., and in any caseshould not be fabove 60o-625 C. The proportions in the mixture admittedin each cycle vare preferably in the explosive range, this, of course,forming only a minor part of the, mixture passing to the catalyticfurnace. Consequently, th`e operation should not be started with thecomplete mixture ,until'later in the starting operation. I will nowdescribe certain experimentswith such apparatus.

'I'he thickness of catalyst layer in vthe rst set ofv tests was 1.27 cm.and itsv area 730 sq. cm. The total. weight of 'catalyst'and asbestos onwhich. itwas deposited was 385 grams.- of which 311`fgramsrwasmolybdenum trioxide.` This ox.- ide usually changes 'into .a complexmixture-of the blue oxides of molybdenum together' with some molybdenumdioxide. y f

From this data the time ofsojourn of l'any'test is calculated as beingthe-.time itv takes an imaginarylayer' of gas, cuil olecule thick, topass through the' catalyst lay That is. the length of travel between/thesc ns holding the cat- 7 alytic mass in placein the test described.The",I y ozonizer wasl bypassed in the following experi- The first setof testa-The first vtest was a straight ilow with no cycling. 'The gasused was a dry'natural gas'containing 85 to 90% of methane.-

The' thickness ofy catalyst,-1.27cm.; area, v730 sq. cm.. T he -mixturewas six .liters of gas perl minute lmixed with six'litersof-.air perminute.

The time of run was ten hours; time of, sojourn 1.8 seconds. The'temperature at the center ofthe catalyst was 425 C. e amount of methane;fed in wasapproximately 2570 grams.

pressure, the pro-f ditions were the same as in the first test.

0n analyzing the gas beyond vth scrubbers, it

was found to contain the following y volume:

y Percent Carbon dioxide .6 Oxygen s 6.4 Unsaturated hydrocarbons 1.2Carbon' monoxide L 1. 2 the balance being largely methane, nitrogen,etc.

The formaldehyde .recovered from the water scrubbers was 7.85 grams,being .31% by weight ing through the catalyst per minute was the same asin the preceding. but was made -up as fonows;

2 liters of fresh methane .fr 100- 2 liters of/fresh air 8 liters ofreturn or tail gas from the scrubbers.l This return gas wasapproximately twoV thirds of the total gas `in circulation,v one-thirdbeing 101is v discarded at each cycling before returning to the inletfromthe scrubbers. This method of feeding reduces the' new hydrocarbonintroduced.' The total methane passing intothe apparatus isl now 857grams in the ten-hour run. Other conl The gas beyond .thescrubbers wasfound to the balance being methane, nitrogen, etc.

There was recovered from thescrubbers 5.97 grams of formaldehyde whichequals .70% pf `the methane passed into the, apparatus. The methane.going -to CO2 was 15.7 grams; that going to1CnHan was 17.1 grams; thatgoing to CO was 125 4.2.8 grams; that going to CHzO was 3.18 grams.

The total methane passe-d into theapparatus dur- 'ing the ten-hour runwas 428 grams. Other con- M0 l ditions were the same as in the firstte'st. In this case, the gasgbeycrnd thescrubbers was:

l. Percent". co2 1.4 oj2 .s 6.41ct cum.; 1..0/ co 2.o

.the balance Cil-I4, N2, etc. i l I 'The total formaldehyde recoveredfrom the 150 scrubbers was 8.64 grams, being equivalent to 1.98% byweight of the lCH4 introduced. The methane passing to CO2 was 12 grams;that passing to CpHan was ,8.5 grams; that passing to CO was 17.1 grams;'that passing to CHzO was 4.52

grams. o

In this case, we obtained approximately' six times as much formaldehydein a ten-hour run from one-sixth as much methane passed' into theapparatus as in the first test, the cycling ratio being 1 to 5. 4 Y fThe fourth test- In this case, the inlet gas was made up ofthree-fourths of a liter of fresh methane per minute; three-fourths-of aliter of fresh air per minute; and ten and one-half liters of return gasper minute. -The total methane passed into the apparatus. during theve-hour run was 161 grams. Other conditions were vthe s ame'as inthelfirst test. In the results, the 'gas beyond the scrubbers showed:

Y. l Percent- CO2 1.7

I 0.2 .1 "`1%... 1. 2.3 CnH2n V 1.2 co l 2.11

the balance heiligen., Leie.

In this case, the total formaldehyde recovered# from the scrubberswas`2.85 grams,being 1.77%

-sion is further supported by the results of the next test.

The flfthtestL-In thiscase,the twelve liters per minute of inlet gaswere made up as follows:

1/2 liter fresh methane per minute 1/2 liter of fresh air per minute 11vliters of return gas per minute.

The total methane passing into the' apparatus in a ve-hour run was 107grams. Otherconditions were the same as in the first test. In theresults, the gas beyond the scrubbers showed:

:Percent C014 2 6 O: 2 3 CnHzn 1 1 CO 2 0 the balance being methane, Na,etc. 4

The total formaldehyde recovered from the scrubbers was`201 grams, being1.88% by weight of methane passed into the apparatus. The percentage ofmethane to CO2 was 5.8 grams; that to cnam. was 2.4 grams; that to cowas 4.2 grams, and that to CHzO was 1.07 grams.

The results of this last testtaken in conjunction with the set ofpreceding tests, vshow that under the given set of conditions, a pointof maximum formaldehyde production was reached ata 'cycling ratioVV ofabout 1.5, with the air and gas at atmospheric pressure.

A run was also made to 'ascertain whether increased temperature wouldincrease `the formal` dehyde yield. In' this case, the time of -sojournwas .995 second, the cycling ratio was 1.9 and the temperature 450 C.,other conditions` being as in the last test. The percentage by weight offormaldehyde obtained, as based on the methane, was only 1.59%.

vBelievingtlrat the third test of the series representedA the bestpercentage of product obtainable with the relatively thick layer ofcatalyst used `and cycling at atmospheric pressure, I decided to changethe catalyst to a thinner layer :and to .get the effect of increasedpressure by using oxygen instead of air. Of course, increasing thepressure in the apparatus will increase the amount of oxygen per unit ofvolume, and the 4same effect is obtainedby introducing oxygen with airor by introducing oxygen alone. In other words, it is desirable to bringinto theimixture. in contact with the catalyst a greater number-ofoxygen and methane molecules in a given time. This is preferably done bycompressing the methane with enough air to obtain the best oxygenmethane molecular volume concentration. To obtain this effect, I madethe following tests where the catalytic layer was one-half as thick asin the first set of tests, and pure oxygen was used instead of air, ahigher temperature being employed. f j

Oxygen test No. 1.Temperature 500 C. The

inlet gas had the followingA composition:

1 "liter per minute of fresh methane 1/2 liter per m'inute of freshoxygen (99%) 16 liters per minute of return gas from the scrubbers,approximately 11/2 liters permin- -ute being discarded between thescrubbers and the inlet before the new gases were introduced, this beingdone at the exit from the constant pressure device for the tail gas.

The time of sojourn was .574 second and the duration of run five hours.the methane introduced was 214 grams, other conditions being similar tothose in the first tests. In these tests, vthe composition of the gasentering the catalytic screen is as follows: carbon dioxide-4.60%;.oxygen-7.40%; olens (CnH2n)-2.`0%; carbon dioxide-3.47%; nitrogen (fromthe commercial oxygen used and from the natural gas used 4.20%; methaneand ethane-78.33%. In the results, I found in the gas beyond thescrubbers:

' Percent CO2 5. O2 1 5. CnHmi ...l 2.2 CO 38 the balance being mostlymethane and some N2.

The weight of formaldehyde recovered from the water-scrubbing, systemwas 14.26 grams, which is 6.65% on the weight of methane introduced. Ofthe methane, 16.2 grams passed to CO2; Y7.1 grams to CnHzn; 12.2 gramsto CO and 7.6 grams to CHzO. The methane actually attacked was 41.3grams and hence, the percentage of methane which was converted to'formaldehyde i?, the methane attacked amounted to 17.63%, whichamounted to 33.04% in` weight of formaldehyde yield based on methaneattacked.l This test shows the marked improvement in formaldehyde yieldobtained by increasing molecular volume concentration of the oxygen andmethane, that is, by having more oxygen and methane molecules in a givenvolume in a given time in the catalytic The total weight of mass.the'diluting elect of the -nitrogen is reduced and almost eliminated.

If, instead of using oxygen, I employ'air under pressure, the nitrogenis, of course, present, but by compression,v I can attain largely thesame as the pure oxygen results by bringing the same or even a greaternumber of oxygen and methane molecules into the volume at, say, apressure of f 100\pounds or more .per square inch on the gas and oxygenentering the reaction zone.

Oxygen test No. 2,-In this case, the inlet gas had:

V2 liter per'minute of fresh methane 1/2 liter per minute fresh oxygen(99%) 19 liters per minute of returngas from the scrubbers,` somewhatless than 1 liter per minute being taken out in a cycle,d1ecause of thecontraction due to more marked oxida# tion in this experiment.

The time'of sojourn was .5 second, the duration of the run' beingintroduced. The result showed in the gas beyond the scrubbers:

Percent O2 22.3 CnHzn I 1.4 CO2 2.8

the remainder being methane, Nn, etc.

The weight of formaldehyde recovered from the water-scrubbing system was11.55 grams, this being 10.8% of the weight of methane introduced. Inthis case,.the.methane attacked was 30.37 grams of which 5.7 grams'passed into forformaldehyde.

maldehyde, which is 18.9% of the methane at tacked. This gave a weightof yield of 38% of formaldehyde based on the methane attacked.

Owing to the large volume change in this test, I believe that thecan'ntbe calculated for scrubbers and is not affected by the volumechangesfthis figure is fairly accurate Higher oxygen concentrationsenable me to cycle a greater number of times, and to further con..- A13.6 OI 7.2' CnH2nf 1.2 .G0 l 3.0

increase the productionI of formaldehydeV beyond that possible with airat atmospheric pressure.

Oxygen' test No. gas had:

.25 liter fresh methane per minute ..25 oxygen (99%) per minute 19.50tail gas returned per minute i This may be called 1`40 cycling. The timeof the run was ve hours and the time of sojourn about .50 second.v Thetemperature was 450 C. The total methane passed in was 52.6 grams. Theexit gas analysis showed:

. Percent the balance being prin7cipally'CH4 with 'some etc. The totalformaldehyde r overedwas 5.9 grams, which makes the perce tage by weightof fdmaldehyde treated to 11.6% or 6% of methane converted toformaldehyde.

Oxygen test No. 4.-A run exactly. like that of` No'. 3V was made, exceptthat the inlet gas mixture was saturated with -moisture at a few.degrees product live hours, 107 grams of methane tions.

distribcion of che medians` the substance other than Since this iscaught in the water 3.-In this case, the inlet lower temperature. Inthis case, the exit gas showed:

v 4 Percent cmp.-. 14.8 Oz 8.4 CnH2n 1.4 CO l 3.2

been established. This test, therefore, represents the actual conversionunder equilibrium condi- In this case, the compositionof the gasentering the atalytic screen was carbon dioxide- 14.25%; `oxygen-8.54%;nitrogen-"3.78%: olens-'1.35%; carbon monoxide-2.95%; methane, etc'.69.13%. In this case, the exit gas analysis showed:

' Percent' CO: 14. 6 Oz 7.5 CnHzn 1.4 -CO f 3.0

'I'he total formaldehyde recovered was 7.16 grams. which is.13.7% of theweight of methanetreated, hence 7.3 of theweight o f the methane wasconverted into formaldehyde. In this case, the methane attacked amounted20% of this passed -into formaldehyde.v

to 19.25 grams and The weight of formaldehyde obtained was therefore37.5% based on the amount of methaneattaked. Oxygen test No. 6.-In thistest, I used a lower oxygen content in the system. 'Ihe mixture was thesame as that in the last tests, except that the inlet mixture contained.3 liter oi'- methane rper minute-and .2 liter of oxygen (99%) perminute,

In this case, the exit gas showed: A

'Percent co2 l 12.8 if O2 3.3

'I'he formaldehyde recovered was 6.93 grams,

which is, 11.1 of the weight of methane' treated,

hence the methane was 5.9%. The mixture in this case was a safer mixturefor actualoperation than in the one preceding. f

'I'hese tests show that to attain a high yield of "formaldehyde, it isnecessary to have in a givenA mixture asmany molecules'of oxyl possiblewithin theLsaiev lvolume of the genand methane as limits of working,hence, these tests show the importance of working wlthair underpressure. in order to obtain this "volume concentration, las the cost ofpure oxygen is relatively high. f

One'of the advantages of of the tail`gas after the condensation and re'-moval of product from tion of the nitrogen dilution where air isemployed.

One ofthe advantages ofcycling lies in the car-A bon dioxide formationland its return to the catalytic chamber. This return` increases theyield converted to formaldehyde the cycle lies in the reductaking out aportion lit uoy

. 1924y as well as in the parentcase, Ser. No. 745,025,

work safely with higher oxygen concentration. I It is important that thenitrogen dilution should not proceed too far, and this is one of theob-J jects of checking out of the system a part of the tail gas afterremoval of the industrial product. It is also important to keepsubstantially constant conditions as to pressure and temperature afterthe system is in fulloperation. 'Ihe system may bel used without acatalyst, although it is far preferable to use a catalyst, and oxidesofl molybdenum are especially good for this purpose. Of cour there maybe a plurality of the catalytic reaction zones included in the cycleinsteadof one, as shown. If more than one is included, each should have\its absorbing system, etc. By the term intensiled oxygen in the claims,I intend to cover and include air under pressure, the use of oxygeneither in air or by itself, or j ozonized air.- By the termhydrocarbons1n the broader claims, I intend to cover either ahydrocarbon or hydrocarbon derivative.

Many changes may be made in the form of the l apparatus and the partsthereof, as well as in mmf the steps within the scope of my broader cAll claims herein arelimited to bleeding out a portion of tail gas andto adding fresh hydrocarbon and oxygen ina continuous recycling process.Other features and combined method steps are included in my UnitedStates Patent No. 1,858,- 095, of May 10, 1932, forming a division ofthe parent case, Ser. No. '745.025, filed October 21,

which is copending herewith.

I claim:

1. In a partial oxidation process, the steps consisting in passing amixture of hydrocarbon and oxygen in gaseous phase through a reactionzone, condensing and removing an oxidized hydrocarbon product from theresulting gas stream,

" "taking a portion of the tail gas out of the system,

adding a fresh portion of hydrocarbon and oxygen, and again passing thenew mixture through a reaction rane and again condensing and removing anoxidized hydrocarbon product from the gas stream.

2. Av process as set forth in claim i, carried out undersuperatmospheric pressure.

3. A process as set forth in claim l, carried out by supplying externalenergy to force circulation of the reaction mixture.

4. In a partial oxidation process, the steps consisting in passing amixture of-hydrocarbon and oxygenin gaseous phase through a reactionzone, condensing and removing an oxidized hydrocarbon product from theresulting gas stream, taking a portion of the tail gas out cf thesystem,

lof formaldehyde by hindering further carbon ,dioxide formation and alsomakes it possible to adding a fresh portion of hydrocarbon and oxygen,again passing the new mixture through a reaction zone, and again.condensing and removing an oxidized hydrocarbon product from the gasstream, while maintaining substantially constant conditions in thestream.

5. A process-as set forth in claim 4 in winch the hydrocarbon of` themixture of hydrocarbon and oxygen in gaseous phase is a hydrocarbon gashaving a plurality of carbon atoms.

6. In a partial oxidation process, the steps consisting in passing amixture of hydrocarbon with oxygen in gaseous phase through a reactionzone in contact with a solid catalyst with a time of sojourn between onequarter'of a second and;

four seconds, removing an ,industrial oxidized hydrocarbon product fromthe resulting gas stream, removing a portion of the tail gas from thestream, adding a fresh portion of hydrocarbon-oxygen mixture, andpassing the fresh mixture again through the reaction zone whilemaintaining substantially'constant conditions in the cycle.

7. In a partial oxidation process, the steps consisting in passing amixture of hydrocarbon and oxygen in gaseous phase through a reactionzone in contact with a catalyst, condensing and removing an oxidizedhydrocarbon product from the resulting gas stream, taking a portion ofthe tail gas out of the system, adding a freshportion of'hydrocarbon andoxygen, again passing the new mixture through a reaction zone,v andagain condensing and removing an oxidized hydrocarbon product from thegas stream;

8. In a partial oxidation process, the steps consisting in passing amixture of hydrocarbon with oxygen in gaseous phase through a reactionzone in contact with a solid catalyst with a time of sojourn betweenone-quarter of a second and one second, removing an industrial oxidizedhydrocarbon product from the resulting gas stream, removing a portionofthe tail gas from the stream, adding a' fresh portion ofhydrocarbonoxygen mixture, and passing the fresh mixture again throughthe reaction zone while maintaining substantially constant conditions inthe cycle.

9. In the manufacture and production of organic compounds containingoxygen by catalytic oxygenation of hydrocarbons in a lcirculatory systemunder pressure and at an elevated temperature and in the presence of acatalyst capable of causing the formation of formaldehyde, the step ofemploying a gas mixture containing a high percentage of an inert gas notrequired for the reaction and continuously removing part of the gas fromthe circulatory system and replacing it by fresh 4gas mixture in suchproportion as to maintain a substantially constant composition of thecirculating gas mixture.

JOSEPH HIDY Jarras.

use

